The flowable medium with which the present invention is concerned can be considered a practically incompressible fluid which can be relatively liquid, somewhat viscous or even a pasty medium. Generally the flowable medium is a lubricant and the apparatus with which the invention is concerned can be used in various technological fields. For example, it can be used in the chemical industry for the metered feed of a flowable medium to form a mixture therewith, even in the case of nonlubricants. Its most important utilization, however, is for the dispensing of a lubricant, such as an oil or grease, to the moving parts of a machine which require the supply of lubricant thereto.
The prior art apparatus over which the invention is an improvement comprises a tubular segment forming the pumping chamber and connected by a checkvalve to the vessel for the flowable medium, the checkvalve closing upon the buildup of pressure in the pumping chamber.
The actuating device for this system can comprise a squeezing plunger which is movable transverse to the axis of the tube segment and bears upon the wall of the flexible tube to displace that wall inwardly and thereby reduce the volume of the pumping chamber to drive the flowable medium through the nozzle.
The actuating lever can bear upon the plunger. The actuating lever in this earlier system can be actuated by hand and the stroke of the actuation can determine the amount of the flowable medium dispensed for the particular stroke, i.e. the metering action.
In many technological fields, the manual actuation of the actuating lever cannot be effected or can be effected only with difficulty or by creating a dangerous situation. This is especially the case with running machinery, in motor vehicles and for motorcycles, for example. It is desirable to provide a system for lubricating the drive chain of a motorcycle, for example, but manual devices close to the moving chain can endanger the user. It is desirable and indeed mandatory for many applications of a dispenser for flowable materials and especially lubricants, that the apparatus be automatically actuatable.